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Cytochrome c oxidase (CcO) is a multimetallic enzyme that carries out the reduction of [O.sub.2] to [H.subq]O and is essential to respiration, providing the energy that powers all aerobic organisms by generating heat and forming ATP. The oxygen-binding heme [a.sub.3] should be subject to fatal inhibition by chemicals that could compete with [O.sub.2] binding. Near the CcO active site is another enzyme, NO synthase, which produces the gaseous hormone NO. NO can strongly bind to heme [a.sub.3], thus inhibiting respiration. However, this disaster does not occur. Using functional models for the CcO active site, we show how NO inhibition is avoided; in fact, it is found that NO can protect the respiratory enzyme from other inhibitors such as cyanide, a classic poison. amyl nitrite | cyanide poisoning | synthetic functional model | EPR

Dietary salt plays a major role in the regulation of blood pressure, and the mineralocorticoid hormone aldosterone controls salt homeostasis and extracellular volume. Recent observations suggest that a small increase in plasma sodium concentration may contribute to the pressor response of dietary salt. Because endothelial cells are (i) sensitive to aldosterone, (ii) in physical contact with plasma sodium, and (iii) crucial regulators of vascular tone, we tested whether acute changes in plasma sodium concentration, within the physiological range, can alter the physical properties of endothelial cells. The tip of an atomic force microscope was used as a nanosensor to measure stiffness of living endothelial cells incubated for 3 days in a culture medium containing aldosterone at a physiological concentration (0.45 nM). Endothelial cell stiffness was unaffected by acute changes in sodium concentration atomic force microscopy | cell stiffness | endothelial dysfunction | eplerenone

Preliminary study has shown that the flue gas recirculation (FGR) is one of the effective ways to reduce the nitric oxides (N[O.sub.x]) emission in industrial furnaces. The sensitivity of the N[O.sub.x] emission from a FGR industrial furnace to the change in three major furnace input variables--inlet combustion air mass flow rate, inlet combustion air temperature, and pressure head of the FGR fan--is investigated numerically in this study. The investigation is carried out in frequency domain by superimposing sinusoidal signals of different frequencies on to the furnace control inputs around the design operating condition, and observing the frequency responses. The results obtained in this study can be used in the design of active combustion control systems to reduce N[O.sub.x] emission. The numerical simulation of the turbulent non-premixed combustion process in the furnace is conducted using a moment closure method with the assumed [beta] probability density function for the mixture fraction. The combustion model is derived based on the assumption of instantaneous full chemical equilibrium. The discrete transfer radiation model is chosen as the radiation heat transfer model, and the weighted-sum-of-gray-gases model is used to calculate the absorption coefficient. [DOI: 10.1115/1.2141636]